Aquaponics - Over Flow

I wandered out to my system last night, and had what is commonly known as an HSM.

It must stand for Holy Ship Moment.

One of my grow beds was flooded, and there didn't seem to be any reason why.

This is the scene a few minutes after the pump was switched off.

There was water on the floor, and the pump was sucking in small air bubble through the little tornado that had formed in the shallow water over the pump inlet.

I couldn't figure out what was going on, so did a search of the system.

I found this blockage in the stand pipe.

It was stuck really well, but eventually to hammer it out with a length of dowel and a hammer.

The culprit, shown here, was a small piece of scoria.

This growbed's media is scoria.

I also found bird droppings. I'm guessing a blackbird was in there throwing things around and looking for worms.

I do actually have an over flow pipe, added when I first built the little system, but the input flow from my bigger pump is much greater these days, so the little pipe wasn't up to the task.

Even so, it's a good thing it was there because I think it saved the day by delaying the disaster until I discovered it.

I'll upgrade the pipe to cope with the new greater flow, and I've put a PVC cap over the media guard so that particular issue cant happen again.





120 Things in 20 years think the last thing an aquaponics system needs is excitement when it comes to overflows.

Aquaponics - Puddle flange

Who would have thought there was a need to call something a "puddle flange"? It turns out there is such a need. In fact, I just bought one.

A flange is normally a thing that flares out from the size of a pipe, to something at right angles to that pipe.  It allows you to connect it to another flange with bolts.

Puddle flange

A puddle flange is a PVC something, that flares out from the size of a pipe, and connects to a puddle.

It turns out, the thing you have in your shower around the drain is a puddle flange.

I found one that has a hole in it that perfectly fits a 50mm PVC pipe.





I'll stick a 50mm pipe into the hole to act as a standpipe, and silicone the puddle flange into the hole that's in the bottom of my new grow bed.

Because I bought a pump with expansion of my system in mind, it's too powerful to need to run it 24/7. I'll be putting my pump on a timer, and running it for perhaps 10 minutes per hour. This means I will probably settle on using a slow leak approach rather than bell siphon approach to drain my grow bed.

The slow leak approach will involve putting a hole in the bottom of the standpipe, just up from the bottom, so that in time all the water will drain out. The standpipe is there as an emergency overflow pipe.

If for some reason the water fails to drain out of the grow bed, on the next cycle, the grow bed might overflow. With a standpipe as an emergency overflow, the grow bed might remain flooded, but the water will overflow back into the sump.

I'll drill a small hole in the standpipe to start and see how long it takes to empty the grow bed. If I need to, I can then drill larger and larger holes, until the grow bed drains over the space of about an hour.

I'll also be setting the drain up so that if at some stage I need to change the system to a bell siphon based one, all I'll have to do is replace the standpipe, and add a bell.

Aquaponics - Overflow pipes

One small but very important detail I left out of the SketchUp diagram in the previous post is overflow pipes. If something goes wrong with the system and the siphons fail because a potato or a snail has made a home in one, it is vital that the water has some way to get back into the sump. The pump in the sump will be damaged if it is run without water.

Overflow pipes are simply pipes that will drain the grow beds before they overflow onto the ground. The pipes are set slightly above where the siphon would normally trigger and run through the side of the grow bed and back to the sump. If for some reason either of the siphons should fail, the water will run back into the sump and keep the system running. It wont be ideal but the fish will be happy and the pump will be happy. The plants should be fine as long as the beds don't stay flooded for too long.

They should never be needed but for the sake of $5 worth of fittings its worth adding them.

For an additional few cents a very small hose can be connected from a hole in the bottom of each grow bed to the overflow pipes so that there is always a small constant stream of water draining from the grow beds to the sump. This is done in case the main pump fails. In the event of the main pump failing, the garden beds could be half full of water and the plants can suffer as a result. The slight leak allows the beds to drain albeit over a few hours.

Main pump fails -
grow beds slowly drain and will be fine for up to 3 days (plants and bacteria) depending on weather.
fish are fine because the powerhead keeps the oxygen levels up.

Power head fails -
doesn't bother the fish as the main pump is still doing it's thing.
doesn't bother the grow beds as they don't get any water from the power head.

Siphon fails -
water overflows through the overflow pipes back into the sump so sump pump is fine.
gardens are flooded but they can take that for a while depending on the plants (eg. lettuce can grow in permanently flooded beds)

Within an aquaponics system its always good to have backups for whatever critical systems you have, especially when they can be done for a relatively small cost.